flashcard vs posting

flashcard and posting both are nouns.

Word	Noun	Adjective	Verb	Adverb
flashcard	Yes	No	No	No
posting	Yes	No	No	No

As nouns, posting is a hypernym of flashcard; that is, posting is a word with a broader meaning than flashcard:

flashcard: a card with words or numbers or pictures that is flashed to a class by the teacher
posting: a sign posted in a public place as an advertisement

Other hypernyms of flashcard include bill, card, notice, placard, poster.

flashcard (noun)	posting (noun)
a card with words or numbers or pictures that is flashed to a class by the teacher	the transmission of a letter
	a sign posted in a public place as an advertisement
	(bookkeeping) a listing on the company's records